The present invention broadly concerns the interconnection of a tractor vehicle and a trailer vehicle. More particularly, the present invention relates to trailer hitch receivers and draw bars that are attached to a tractor vehicle so that a trailer vehicle may be secured thereto for towing. The present invention specifically relates to a draw bar that is mounted in a standard hitch receiver yet which provides for a cushioning of forces encountered during the towing operation.
Since the advent of engine powered vehicles, there has been a recognized use for such a vehicle as a xe2x80x9ctractor vehiclexe2x80x9d in towing an un-powered or xe2x80x9ctrailer vehiclexe2x80x9d. Typically, the tractor vehicle and the trailer vehicle are releasably coupled together by means of a releasable coupling. Such couplings provide matable mechanical structures that may be secured or locked during the towing operation yet may be unsecured or unlocked so that the tractor and trailer vehicles may be separated from one another.
One such coupling that has been used for numerous years includes a ball hitch that is mechanically secured to the frame of the tractor vehicle. The ball hitch includes a spherical ball portion mounted on a shaft. The trailer vehicle is then provided with a tongue that has a ball receiver in the form of a cylindrical cavity sized and adapted to nestably receive the spherical portion of the hitch ball and to be latched thereon while the trailer vehicle is being towed. Hitch balls can be of varying diameters and must be matched with the hitch receiver of the trailer vehicle.
One very popular type of trailer hitch employs a hitch receiver that is affixed to the frame of the vehicle. This hitch receiver is commonly in the form of an elongated hollow, tubular member that is typically of a square-shaped cross-section. The longitudinal axis of this elongated tube is oriented in the direction of travel of the tractor vehicle. A pair of aligned bores are formed in the side wall of the hitch receiver so that a hitch pin may be passed therethrough and clipped or locked into position. A draw bar is provided and is formed as an elongated shank that is adapted to be telescopically received within the interior of the hitch receiver in close-fitted engagement. This shank supports a mounting structure that includes the hitch ball that may be mated with the ball receiver of the trailer. In any event, the shank is provided with a transverse bore of similar size to the bores in the hitch receiver so that, when inserted in a mated state within the hitch receiver, the hitch pin may extend through the bores both of the hitch receiver and of the shank thereby to releasably link them together. With such construction, the user may remove and store the draw bar when the tractor vehicle is not towing a trailer vehicle.
Hitch assemblies of the type described above often have a rigid, metal-to-metal interconnect between the draw bar and the hitch receiver by way of the hitch pin. That is, the hitch pin is in shear between the walls of the hitch receiver and the draw bar. As a result of this rigid interconnect, shock and vibrations result between the trailer vehicle and tractor vehicle. These shocks and vibrations arise from acceleration and braking of the vehicles as well as road surface bumps and vibrations as well as the relative roll of the tractor vehicle and the trailer vehicle rotationally about the axis of travel. As a result, the tractor vehicle is exposed to jerking starts and stops as well as other vibrational forces from the trailer vehicle. Not only can these problems create an unpleasant driving experience, but also can cause wear and tear on the hitch assembly. This in turn, can create a concomitant danger to the driver and passengers of the tractor vehicle as well as to others in the driving environment.
It has been known in the past to address the issue of the rigid interconnect between the tractor and trailer vehicles. For example,
For example, U.S. Pat. No. 4,817,978 issued Apr. 4, 1989 to James discloses a trailer hitch assembly of the draw bar type consisting of a receiver tube mounted on the tow vehicle to receive a draw bar tube in vibration dampened retention while extending a hitch ball. The draw bar tube encloses a resilient spring block assembly that is secured to the receiver tube by means of a hitch pin. The hitch pin moves with an elongated slots on the draw bar tube so that vibration from the draw bar tube is damped by the spring block assembly and isolated from the receiver tube and tow vehicle. A shock absorber is also interconnected between the receiver tube and a point on the draw bar tube.
U.S. Pat. No. 4,773,668 issued Sep. 27, 1988 to Muonro discloses a towing hitch that has a housing for receiving a tow bar such that the housing can be pivotally connected to the tow bar. A tongue is coupled to the housing for receiving the towing element, and the housing has a pin which projects into the tow bar. The pin has a resilient block mounted thereon such that the block is arranged between the pin and the tow bar to dampen or absorb shock or vibration transmitted to the towing hitch. The above referenced patents show the use of resilient pieces to dampen vibration between a tractor vehicle and a towing vehicle. In addition to these patents, other patents have described tow hitch assemblies to dampen various motions. These include:
In U.S. Pat. No. 5,823,560 issued Oct. 20, 1998 to Van Vleet, a trailer hitch apparatus is shown that includes dampening mechanisms to simultaneously dampen vibration and shock in a longitudinal direction and a vertical direction. The apparatus included a hollow draw bar tube capable of being removably coupled to a hitch receiver of a tractor vehicle. The draw bar tube is movably longitudinally relative to the receiving tube while secured therein by means of a hitch pin. The hitch pin extended through a slide block movably disposed in the hollow draw bar, and dampening cushions were placed on either side of this slide block so as to cushion its longitudinal movement. Thus, the hitch pin was rigidly mounted to the slide block which in turn was resiliently biased within the draw bar. These cushions, then, dampened longitudinal movement both during acceleration and deceleration of the tractor vehicle and the trailer vehicle.
While the structures shown in U.S. Pat. No. 5,823,560 provided a substantial improvement over previous dampening mechanisms, there remains a need for increasingly better systems that can accept and attenuate the relative forces between the tractor vehicle and the trailer vehicle that are caused by acceleration, deceleration and the other force causing conditions noted above. There is a further need for trailer hitch receivers and draw bars that have dampening mechanisms that are easy to assembly and use. There is a further need for such systems that can provide a variety of cushioning systems that can be customized to different load conditions between the tractor and trailer vehicle. The present invention, in its various embodiments, addresses these issues.
It is an object of the present invention to provide a new and useful trailer hitch assembly adapted to interconnect a tractor vehicle and a trailer vehicle.
It is a further object of the present invention to provide a new and useful draw bar that is adapted to mate with a hitch receiver and a combination draw bar and hitch receiver wherein the draw bar is cushioned with respect to longitudinal forces.
It is yet another object of the present invention to provide a new and useful method of hitching a trailer to a tractor vehicle.
A still further object of the present invention is to provide a hitch assembly that cushions one or more of the forces occuring during the interaction between a trailer vehicle and a tractor vehicle.
Yet a further object of the present invention is to provide a method and apparatus for hitching a trailer vehicle to a tractor vehicle, if desired, can be modified to accommodate different loads between the vehicles.
Accordingly, to the present invention, then, a draw bar and a trailer hitch incorporating such a draw bar is provided. Broadly, the draw bar includes an elongated shank that has a longitudinal axis and that has a transverse throughway extending therethrough. The throughway has parameter wall portions, and a resilient cushion member is movably disposed in the throughway and is supported against the parameter wall portions of the throughway. A passageway is associated with cushion member and is sized to receive a hitch pin such that when in the mated state, longitudinal motion of the shank in the hitch receivers resisted by the cushion member with resilient force. When used in a hitch assembly, a hitch receiver is provided that is adapted to be secured to the tractor vehicle. Here, the hitch receiver defines a longitudinally extending cavity and includes a pair of receiver side walls. A bore is formed in each of these side walls with the bore being sized for close-fitted engagement by the hitch pin when in the mated state. These bores are thus axially aligned so that, when the draw bar is inserted within the hitch receiver, the hitch pin can extend through the bores and through the passageway that is associated with the cushion member thereby to secure the draw bar in the hitch receiver.
The draw bar has a shank that can be formed either as a hollow tubular member or as a solid piece. When the shank is formed as a hollow tubular member, the throughway is defined by a pair of opposed openings. Each of these openings has a first edge portion and a second edge portion that define at least some of the parameter wall portions that support the resilient cushion member. When the shank is solid, the throughway has first and second side wall portions oriented transversely of the shank with these side wall portions then supporting the cushion member.
While the cushion member may be directly supported by the parameter wall portions, either in the form of the edges of the hollow tubular shank or the side wall portions of the solid shank, the present invention contemplates the indirect support of the cushion members by means of a cartridge. Here, the cartridge is formed by a rigid casing that is sized and adapted to be received in the throughway. The casing is then supported against movement in the shank by the first and second side wall portions or edges of the shank. The resilient cushion member is received in the casing and is supported thereby.
In a more detailed form of the present invention, a slide member is disposed in the throughway and, preferably, in the cartridge casing so that it is reciprocally moveable therein in a longitudinal direction. The slide member has a transversely extending bore that is sized and adapted to receive the hitch pin when in the mated state. The cushion member is disposed between the slide member and one of the first and second end wall portions of the opening in the casing.
In order to cushion both acceleration and braking forces between a tractor and a trailer vehicle, it is desired that a pair of cushion members be disposed in the cartridge or within the throughway. Here, there is a cushion member on each side of slide member so that the slide member is resiliently supported for longitudinal movement in opposite directions against opposite forces.
If desired, the cushion members can have different resiliency characteristics. Different resiliency can result from the formation of the first and second cushion members out of different materials. Alternatively, the resiliency can be differed by providing the first and second cushion members with different geometric shapes. Further, the difference in resiliency characteristics can be provided by constructing the cushion members differently.
In order to accommodate different use demands, a draw bar according to the present invention can employ a system of interchangeable cartridges that are each adapted to be disposed in the throughway and supported from movement thereagainst. At least a plurality of such cartridges would include a casing in the form of a rigid sleeve having an axis oriented transversely to the longitudinal direction with at least one resilient cushion member disposed in the casing. At least some of these cartridges would then have cushions of different resiliency characteristics. Thus, for example, one could provide a difference in resiliency between a braking force and an acceleration force as desired. This would also accommodate cushioning of different load forces when the trailer vehicle is loaded either heavy or lighter. In any event, it is desirable that the draw bar be provided with a hitch ball secured to the shank.
Finally, the present invention includes a method of hitching a trailer to the tractor vehicle. Here, the method includes any of the steps that are accomplished by the structure summarized above. In its broad form, the method includes the placing of a hitch receiver on a tractor vehicle with this hitch receiver defining a longitudinally extending cavity. Here, the hitch receiver again includes a pair of side wall each having a bore sized for close-fitted engagement by a hitch pin when in the mated state with these bores being transversely aligned. The method also includes the step of providing a draw bar that includes an elongated shank having a longitudinal axis in a transversely extending throughway. The method then includes the step of providing at least one cartridge that is adapted to be disposed in the opening and supported against movement therein. The method then includes the step of interconnecting the hitch receiver and the draw bar with the hitch pin in such a manner that the hitch pin is resiliently cushioned relative to said cartridge. Finally, the broad method includes the attachment of a tongue of the trailer to the draw bar.
Additional steps to the method can include the step of providing a plurality of cartridges that are interchangeable within the throughway. Some of these cartridges may have cushioning elements that are of different resiliency characteristics as described above.
These and other objects of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of the exemplary embodiment of the present invention when taken together with the accompanying drawings, in which: